The present invention relates generally to systems for supplying and controlling fluid flow, and in particular to medical infusion technology, although other embodiments are possible.
The invention provides a system for dispensing fluid at relatively constant pressure. In a first embodiment, the invention dispenses a fluid from a chamber of varying dimension defined by a pre-tensioned resilient membrane. In a second embodiment, the invention dispenses a fluid from a chamber defined by a dispensing membrane, which is substantially surrounded by another fluid contained within a pressure chamber of varying dimension defined by a pre-tensioned resilient membrane. In a third embodiment, the invention dispenses multiple fluids, a first fluid from a first dispensing chamber of varying dimension defined by a pre-tensioned resilient membrane, and a second fluid from a dispensing chamber of varying dimension defined by a dispensing membrane substantially surrounded by the first fluid. In a fourth embodiment the invention dispenses multiple fluids from at least two dispensing chambers of varying dimension each substantially surrounded by the pressure fluid contained within a pressure chamber of varying dimension defined by a pre-tensioned resilient membrane.
In a preferred embodiment, the resilient membrane is pre-tensioned beyond the point at which, as fluid enters the volume contained by the membrane and the volume increases, the first derivative of pressure over volume becomes zero for the first time.